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use super::utils::derefs_to_slice;
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::get_parent_expr;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::is_type_diagnostic_item;
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
use rustc_span::sym;
use super::GET_UNWRAP;
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &hir::Expr<'_>,
recv: &'tcx hir::Expr<'tcx>,
get_arg: &'tcx hir::Expr<'_>,
is_mut: bool,
) {
// Note: we don't want to lint `get_mut().unwrap` for `HashMap` or `BTreeMap`,
// because they do not implement `IndexMut`
let mut applicability = Applicability::MachineApplicable;
let expr_ty = cx.typeck_results().expr_ty(recv);
let get_args_str = snippet_with_applicability(cx, get_arg.span, "..", &mut applicability);
let mut needs_ref;
let caller_type = if derefs_to_slice(cx, recv, expr_ty).is_some() {
needs_ref = get_args_str.parse::<usize>().is_ok();
"slice"
} else if is_type_diagnostic_item(cx, expr_ty, sym::Vec) {
needs_ref = get_args_str.parse::<usize>().is_ok();
"Vec"
} else if is_type_diagnostic_item(cx, expr_ty, sym::VecDeque) {
needs_ref = get_args_str.parse::<usize>().is_ok();
"VecDeque"
} else if !is_mut && is_type_diagnostic_item(cx, expr_ty, sym::HashMap) {
needs_ref = true;
"HashMap"
} else if !is_mut && is_type_diagnostic_item(cx, expr_ty, sym::BTreeMap) {
needs_ref = true;
"BTreeMap"
} else {
return; // caller is not a type that we want to lint
};
let mut span = expr.span;
// Handle the case where the result is immediately dereferenced
// by not requiring ref and pulling the dereference into the
// suggestion.
if_chain! {
if needs_ref;
if let Some(parent) = get_parent_expr(cx, expr);
if let hir::ExprKind::Unary(hir::UnOp::Deref, _) = parent.kind;
then {
needs_ref = false;
span = parent.span;
}
}
let mut_str = if is_mut { "_mut" } else { "" };
let borrow_str = if !needs_ref {
""
} else if is_mut {
"&mut "
} else {
"&"
};
span_lint_and_sugg(
cx,
GET_UNWRAP,
span,
&format!(
"called `.get{0}().unwrap()` on a {1}. Using `[]` is more clear and more concise",
mut_str, caller_type
),
"try this",
format!(
"{}{}[{}]",
borrow_str,
snippet_with_applicability(cx, recv.span, "..", &mut applicability),
get_args_str
),
applicability,
);
}
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